Process of forming iron foils



Patented Dec. 30,- 1930 UNITED STATES PATENT OFFICE JOHN R. CAIN, OF WASHINGTON, DISTRICT COLUMBIA, ASSIGNOR TO THE RICHARD- SON COMPANY, OF LOCKLAND, OHIO, A CORPORATION OF OHIO PROCESS OF FORMING IRON FOIIIS ,li'o Drawing.

My invention relates to a. rocess of forming iron foils and other foils iy electro-deposition of the desired metal upon a thin foillike body of copper, followed by the removal by electro-chemical means of the copper, leaving the iron foil or other metal intact.

The steps involving the deposition of iron or other metalon the copper, do not involve any particularly novel subject 'ihatter. In dealing with iron, I will describe a preferred process for electro-deposition.

The process is particularly valuable in connection with the removal of the copper base from the metal foil deposited upon it, and to this, my specification is particularly di rected. In the value so far developed of my I process, I refer particularly to the formation of iron foils, since to produce very thin foils of iron, is a problem in the arts, which has not 20 been satisfactorily solved, .so far as I am advised, and in fine electrical equipment, the foils of electrolytic iron have a high value. To describe a typical process, a sheetof copper foil or thin copper sheet material is immersed in an electrolyte suitable to plate the required metal on the copper. In plating iron, I have employed a copper sheet of three thousandths thickness in a ferrous sulphatesodium sulphate electrolyte, practically neutral'and kept at around 95 to 100 degrees centigrade.

The copper sheet as cathode is suspended or supported in the bath so that to the minimumdegree can the current cause plating on the back of the copper cathode. As an anode I may employ ingot iron, particularly the brand known as Armco ingot iron, which is a commercially pure product. By using a spacing'of around one inch, and continuing the plating at suitable current densities for between sixand ten minutes, I produce a film of iron on the cathode, without any substantial treeing. Agitation during plating, and a flow of electrolyte with a filter to remove precipitated substances is preferred;

The cogper cathode is cleaned and bright I on the sur ace on which platin is to be done, and by a suitable placing in t e bath, I am able to avoid a coating of the back. of the cathode with a high melting point wax, which 1926. Serial No. 115,405.

would otherwise be required, in order to give the best physical qualities to the iron. There are other methods of localizing electrolytic action, however, which I may employ, such as shields, or placing two cathodes back to back,

/ between two anodes.

In stripping, I employ a concentrated solution of alkaline cyanide, such as potassium or sodium cyanide or both, and referably maintain the solution as hot as t e original electrolyte. I'pass a current of medium or low density through the plated copper sheet, as

an anode, and a suitable copper body as a cathode, and thusstrip away the copper quite rapidly, leaving the iron intact. It is preferable to agitate the bath gently. Ifdesired the copper stripped from the cathode may be re-depositedon another finished article, e. g., on. a copper foil, in order to thicken it.

In order to remove any spots of iron that may have plated on the copper back of the plated body, I may coat the iron face with paraifin, dip the body into concentrated V nitric acid, and thus eat away the iron deposits not protected by the paralfin. The paraflin can be left on the iron side, and can be removed by dipping into hot water after the copper has been driven away from it.

I find that the face of the iron next to the copper is quite bright, and that the physical properties of the iro11' foil are good even without any annealing or cold rolling, although it will be best to follow the process of producing the foil by suitable cold rolling.

If the original electrolyte is not hot while the plating is being done, the iron deposit will bejbrittle, which suggests itself as a mode of procedure in stripping the iron away from the copper by starting the plating with the ferrous sulphate-sodium sulphate electrolyte cold, and thus obtaining a first deposit of brittle iron, followed by an elecvtro-deposition while the electrolyte is hot.

siveness of the brittle underneath coating thereof. I state this point without having proven its value, as indicating one of the aspects of my invention in the plating of iron onto suitable cathodes.

The practice of plating other metals on copper, whereof value 1n my invention, would have to be confined to those metals which would not strip away with the cyanide action.

I have not been able to efiect a suitable process for removing a copper base from a product plated with iron, as described, by the use of acids as chemical reagents, without electric current, nor by the use of acid solutions or alkaline solutions, which suggest themselves from electro-plating practice In the use of acid to dissolve a backing of copper from a protected iron deposit, the action is not subject to sufiicient control t produce a good product.

In my product, the iron in particular is malleable, and of one very smooth, practically polished surface.

If it, is desired to plate further iron on the removed foil of my process, it will usually be necessary to confine the additional plating to the smooth surface thereof, or else to cold roll the product so as to give two smooth surfaces.

. Having thus described my invention, what 1 claim as new and deslre to secure by Letters Patent, is

The process of-producing iron foil which consists in electro-depositing iron upon a base of bright, clean copper, and then removing the copper electrol tically in a cyanide solution resulting in a oil having a polished appearance.

' JOHN R. CAIN. 

